Method of manufacturing stamper for manufacturing information medium, stamper, and photoresist master

ABSTRACT

A stamper with a sharp uneven pattern for manufacturing high precision information media and a method of manufacturing a stamper. The method includes (1) manufacturing a photoresist master by forming a light absorption layer and a photoresist layer on substrate, (2) forming a latent image on the photoresist layer, and an uneven pattern in the photoresist layer by developing the latent image, (3) forming a Ni thin film on the uneven pattern by electroless plating, (4) forming a Ni film on the Ni thin film, and (5) removing the Ni thin film and the Ni film from the photoresist master. The method also includes, prior to the step of forming the Ni thin film on the photoresist layer, a metal catalyst being provided on the surface of the uneven pattern, the metal catalyst being activated, and the surface of the uneven pattern being washed with ultra pure water.

TECHNICAL FIELD

The present invention relates to a stamper used during the manufactureof an information medium such as an optical disc comprising an unevenpattern such as grooves and prepits, a photoresist master formanufacturing the stamper, a method of manufacturing the stamper usingthe photoresist master, and an information medium manufactured using thestamper.

BACKGROUND ART

Optical discs, which represent one type of information media, arecurrently available in two different varieties: optical recording discswhich enable writing or rewriting of information, and read-only discs inwhich the information has been pre-recorded onto the disc.

A groove (guide channel) that is used for tracking and the like isformed in the disc substrate of an optical recording disc, and arecording layer comprising a phase change material or an organic dyematerial is laminated on top of the disc substrate. When the laser beamis irradiated onto the recording layer, the recording layer undergoes achemical or physical change, thus forming a recording mark. In contrast,in the case of a read-only disc, recording marks (information pits) areformed in advance as part of an uneven pattern on the disc substrate.When a reading laser beam is irradiated onto these recording marks, thequantity of reflected light varies, and by detecting these variations,the information is able to be read (played back).

In order to manufacture a disc substrate with an uneven pattern ofgrooves, information pits, and the like, a stamper is used in which thenegative pattern (which is itself a type of uneven pattern) of thedesired uneven pattern has been formed. For example, a method ofmanufacturing a disc substrate by conducting injection molding using amold with the above stamper secured inside the cavity, therebytransferring the negative pattern to the resin used to fill the cavity,is common.

A stamper with an uneven pattern is usually formed from a metal stampercontaining Ni or the like. In the steps required for manufacturing thisstamper, first a photoresist master with the negative pattern of theuneven pattern of the stamper is prepared, and a metal film is thenformed on this photoresist master by plating. Subsequently, the metalfilm is separated from the photoresist master, and then subjected to aseries of predetermined treatments such as surface washing to form thestamper.

As follows is a description of the manufacturing process for aphotoresist master 1, with reference to the conventional photoresistmaster 1 shown in FIG. 7. First, a photoresist layer 4 is formed on topof a glass substrate 2. Next, the photoresist layer 4 is exposed using apatterning laser beam such as a laser, and the latent image pattern isdeveloped. This enables the production of the photoresist master 1 withan uneven pattern 6 formed in the photoresist layer 4.

In order to use this photoresist master 1 to prepare a stamper 20 byplating, first, as shown in FIG. 8, a thin metal film 8 containing a Nimaterial or the like is formed on the surface of the uneven pattern 6using a process such as electroless plating, thereby impartingconductivity to the photoresist master 1.

Subsequently, electroplating is conducted with the thin metal film 8 asa backing, thereby forming a metal film 10 containing Ni or the like. Byremoving the thin metal film 8 and the metal film 10 from thephotoresist master 1, a stamper 20 containing the transferred unevenpattern 6 can be obtained.

In recent years, as the capacity of optical recording media hasincreased, uneven patterns such as grooves have become much finer,meaning errors in the pattern shape have a large effect on the recordingand reading accuracy. Accordingly, it is desirable to form a sharpuneven pattern on the disc substrate, but in order to achieve this sharppattern, the uneven pattern of the photoresist layer 4, which is thebasis for the pattern, must be formed with a high level of precision(sharpness).

The minimum width of the latent image pattern formed on the photoresistlayer 4 is limited by the spot diameter of the laser beam when itreaches the photoresist layer 4. When λ is the laser wavelength, and NAis the numerical aperture of the objective lens of the irradiatingoptical system, then the spot diameter w is represented by the formulaw=k·λ/NA. k is a constant that is determined by the aperture shape ofthe objective lens and the intensity distribution of the incident lightbeam.

However, even in the case of patterns with widths that theoretically donot exceed the spot diameter limit, if the photoresist layer 4 is thin,then problems of inadequate sharpness can arise due to factors such asshallowness of the uneven pattern transferred to the stamper, orrounding of the shape of the uneven pattern (this is known as patternsag). It is thought that these problems are caused by fluctuationsoccurring in the thickness of the photoresist layer 4 (this is known asfilm thinning) during typical exposure and developing operations. It isthought that these thickness fluctuations are caused by laser beamreflection between the photoresist layer 4 and the glass substrate 2,with this reflection causing excessive exposure of the photoresist layer4.

The inventor of the present invention has clarified that forming a lightabsorption layer between the glass substrate 2 and the photoresist layer4 is an effective way of resolving these problems. By so doing, thelight absorption layer can absorb the laser beam and suppress any lightreflection, and consequently a sharper exposure and development can beachieved than in a conventional process.

However, based on further research, the inventor of the presentinvention noticed that a photoresist master 1 with a light absorptionlayer displayed some problems relating to the formation of the thinmetal film 8 by electroless plating. Specifically, it was surmised thata photoresist master 1 in which the light absorption layer was partiallyexposed was prone to increases in fine irregularities (fine defects)during the electroless plating process. In other words, it wasdiscovered that even though the same method was used to form the thinmetal film, on some occasions when the stamper was removed, for somereason or other fine irregularities (fine defects) had been formed onthe surface of the uneven pattern of the stamper. During playback thesefine irregularities manifest as noise, meaning that despite the attemptto improve the recording capacity by effectively utilizing a lightabsorption layer, in reality a decrease occurs in the recording andplayback performance.

If this problem can be resolved, then the manufacture of a stamper witha sharp uneven pattern should be possible using a photoresist masterwith a light absorption layer. In other words, it became clear that asharp uneven pattern that had been formed on the photoresist masterthrough the effects of the light absorption layer, could be transferredfaithfully to a stamper.

DISCLOSURE OF THE INVENTION

The present invention is directed to a solution to the above describeddisadvantage, and it is an object of the present invention to provide amethod of manufacturing a photoresist master in which shape errors aresuppressed during the electroless plating process, as well as aphotoresist master, a stamper manufactured using such a photoresistmaster, and an information medium manufactured using such a stamper.

As a result of intensive research on methods of manufacturinginformation media such as optical discs and magnetic discs (discretemedia), the inventor of the present invention discovered a method offorming a sharp uneven pattern on a stamper. In other words, the aboveobject can be achieved by the present invention described below.

-   (1) A method of manufacturing a stamper for manufacturing an    information medium, comprising the steps of: manufacturing a    photoresist master by forming at least a light absorption layer and    a photoresist layer, in that order, on top of a substrate,    irradiating light onto said photoresist layer to form a latent image    from an opposite surface to that which contacts said light    absorption layer, and then developing said latent image to form an    uneven pattern; forming a thin metal film on top of said uneven    pattern of said photoresist master;

forming a stamper by forming a metal film on top of said thin metalfilm, and separating said thin metal film and said metal film from saidphotoresist master; and providing a metal catalyst on a surface of saiduneven pattern, activating said metal catalyst, and then washing thesurface of said uneven pattern on which said metal catalyst is providedwith a liquid, as preliminary treatments to the step of forming saidthin metal film on said photoresist layer.

-   (2) The method of manufacturing a stamper for manufacturing an    information medium according to (1), wherein

pure water is used as said liquid for said washing.

-   (3) A stamper for manufacturing an information medium, in a surface    of the stamper an uneven pattern being formed in advance, the    stamper being manufactured by the steps of: manufacturing a    photoresist master by forming at least a light absorption layer and    a photoresist layer, in that order, on top of a substrate,    irradiating light onto said photoresist layer to form a latent image    from an opposite surface to that which contacts said light    absorption layer, and then developing said latent image to form an    uneven pattern; forming a thin metal film on top of said uneven    pattern of said photoresist master; forming the stamper by forming a    metal film on top of said thin metal film, and separating said thin    metal film and said metal film from said photoresist master; and    providing a metal catalyst on a surface of said uneven pattern,    activating said metal catalyst, and then washing the surface of said    uneven pattern on which said metal catalyst is provided with a    liquid, as preliminary treatments to the step of forming said thin    metal film on said photoresist layer.-   (4) The stamper according to (3), wherein

pure water is used as said liquid for said washing.

-   (5) A photoresist master comprising a substrate, a light absorption    layer laminated on top of said substrate, and a photoresist layer    which is laminated on top of said light absorption layer and is    capable of having an uneven pattern formed therein by forming and    subsequently developing of a latent image, wherein an activated    metal catalyst is provided on a surface of said uneven pattern    formed in said photoresist layer, and the surface of said uneven    pattern on which said metal catalyst has been provided is washed    with a liquid.-   (6) An information medium, in which a final uneven pattern is formed    by using, as a negative pattern, an uneven pattern of a stamper    manufactured by the steps of: manufacturing a photoresist master by    forming at least a light absorption layer and a photoresist layer,    in that order, on top of a substrate, irradiating light onto said    photoresist layer to form a latent image from an opposite surface to    that which contacts said light absorption layer, and then developing    said latent image to form an uneven pattern; forming a thin metal    film on top of said uneven pattern of said photoresist master;    forming a stamper by forming a metal film on top of said thin metal    film, and separating said thin metal film and said metal film from    said photoresist master; and providing a metal catalyst on a surface    of said uneven pattern, activating said metal catalyst, and then    washing the surface of said uneven pattern on which said metal    catalyst is provided with a liquid, as preliminary treatments to the    step of forming said thin metal film on said photoresist layer.-   (7) The information medium according to (6), wherein

said final uneven pattern is formed by direct transfer of said unevenpattern from said stamper.

-   (8) The information medium according to (6), wherein

said final uneven pattern is formed by transfer of an uneven patternfrom a mother stamper, and said uneven pattern of said mother stamper isformed by transfer of said uneven pattern using said stamper as a masterstamper.

-   (9) The information medium according to (6), wherein

said final uneven pattern is formed by transfer of an uneven patternfrom a child stamper, and said uneven pattern of said child stamper isformed by transfer of an uneven pattern from a mother stamper, which hasbeen formed by transfer of said uneven pattern using said stamper as amaster stamper.

The inventor of the present invention applied a metal catalyst to aphotoresist master using a light absorption layer. As a result, theinventor discovered that the synergistic effect of the advantagesoffered by the light absorption layer and the provision of the metalcatalyst enabled the formation of an uneven pattern with bettersharpness than that obtainable by conventional processes. Noticing thefact that a photoresist master in which the light absorption layer ispartially exposed can be prone to increases in fine irregularities (finedefects) during the electroless plating process, the inventor of thepresent invention investigated in further detail, and discovered that bywashing the uneven pattern surface with a liquid following applicationof the metal catalyst, an even finer uneven pattern could be producedwith even better accuracy.

The reason for this observation is thought to be as follows, althoughthis is only conjecture.

Following application of the metal catalyst, during removal of Sn usingan accelerator, the accelerator penetrates into the partially exposedlight absorption layer, reaching as far as the glass substrate surface.At this point, the coupling agent layer that is normally applied to thesurface of the glass substrate undergoes some form of reaction with theaccelerator, generating a gas and causing the formation of fineirregularities. In the present invention, following the acceleratorprocess, the accelerator is washed away by washing with a liquid, andconsequently fine irregularities do not develop. As a result, the unevenpattern, which is exposed with good sharpness due to the characteristicsof the light absorption layer, can be accurately reproduced in the thinmetal film formed by electroless plating.

As a result, the grooves, information pits, and the like of an opticalrecording medium can also be formed with good sharpness, and this makesit possible to improve the recording and playback characteristics.Furthermore, because the invention is compatible with future ongoingminiaturization of uneven patterns, it also enables increases in theinformation memory (recording) capacity of information media.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a photoresist master accordingto an embodiment of the present invention;

FIG. 2(A) is a cross-sectional view showing a state during themanufacture of a stamper using the same photoresist master;

FIG. 2(B) is a cross-sectional view showing the manufactured stamper;

FIG. 3(A) is a diagram showing the result of an AFM analysis of theuneven pattern formed on a stamper according to an example of thepresent invention;

FIG. 3(B) is a line diagram showing the cross-sectional shape of theuneven pattern determined on the basis of the AFM analysis;

FIG. 4(A) is a diagram showing the result of an AFM analysis of theuneven pattern formed on a stamper according to a comparative example ofthe present invention;

FIG. 4(B) is a line diagram showing the cross-sectional shape of theuneven pattern determined on the basis of the AFM analysis;

FIG. 5 is a line diagram showing the uneven state of the stamper surfaceof the above example, as measured by a scanning electron microscope;

FIG. 6 is a line diagram showing the uneven state of the stamper surfaceof the above comparative example, as measured by a scanning electronmicroscope;

FIG. 7 is a cross-sectional view showing a conventional photoresistmaster; and

FIG. 8 is a cross-sectional view showing a state during the manufactureof a stamper using the same conventional photoresist master.

BEST MODE FOR CARRYING OUT THE INVENTION

As follows is a detailed description of an embodiment of the presentinvention, based on the drawings.

FIG. 1 shows a photoresist master 100 according to the embodiment of thepresent invention. This photoresist master 100 comprises a glasssubstrate 102, a light absorption layer 103 laminated on top of thisglass substrate 102, and a photoresist layer 104 laminated on top ofthis light absorption layer 103. Incidentally, the surface of the glasssubstrate 102 is treated with a coupling agent or the like in order toimprove the adhesion to the light absorption layer. A latent image of anuneven pattern is formed on the photoresist layer 104, on the oppositeside from the light absorption layer 103 (the top side in FIG. 1), byexposure with a patterning laser beam, and development of this latentimage causes the removal of a portion of the photoresist layer, formingan uneven pattern 106. Following developing, portions of the lightabsorption layer 103 are exposed at the bottom surfaces of the concavesections of the uneven pattern 106. The numeral 107 in FIG. 1 shows anon-uneven area in which the uneven pattern has not been formed.

As described below, the aforementioned uneven pattern 106 becomes thepattern surface 206 of a stamper 120. Furthermore, the area in which theuneven pattern has not been formed becomes the mirror surface 207 of thestamper 120. During exposure, the patterning laser beam is absorbed bythe light absorption layer 103, thereby suppressing light reflection andenabling the formation of fine unevennesses with good sharpness.

Pd (106A) is provided on the surface of the uneven pattern 106 of thephotoresist master 100. Specifically, a metal catalyst (a Pd—Sncompound) is adsorbed onto the surface of the uneven pattern 106, and anaccelerator is used to activate the catalyst and remove only the Sn,leaving the Pd deposited on the surface of the uneven pattern 106.Subsequently, the surface of the uneven pattern 106 on which the Pd hasbeen provided is washed with a liquid. Specifically, by washing thesurface of the uneven pattern 106 with pure water, and preferably withultra pure water, the development of fine irregularities can besuppressed. The flow rate of the ultra pure water is preferably at least1 l/min, and even more preferably 5 l/min or greater. In this embodimenta Pd-Sn compound was used as the metal catalyst, but the presentinvention is not limited to this case, and other metal catalysts mayalso be used.

Furthermore, in FIG. 1, the Pd (106A) is shown schematically as a thinfilm, but this does not represent the actual state of the Pd.

FIG. 2(A) shows the stamper 120 formed using the above photoresistmaster 100.

In this formation process, first electroless plating is used to form aNi thin film 108 on the surface of the uneven pattern 106 on which thePd has been deposited.

During this formation, a reducing agent in the plating solution isoxidized at the Pd surface, which possesses catalytic activity, andemits an electron, and this electron reduces a Ni ion in the solution,enabling the Ni thin film 108 to effectively conform to, and follow theuneven pattern 106. In this embodiment, adequate quantities of Pd arealso provided within the concave sections of the uneven pattern 106,meaning the Ni thin film 108 can be formed in a manner that faithfullyfollows the uneven pattern 106.

Subsequently, a current is passed through the surface, using the Ni thinfilm 108 as a backing, and electroplating is carried out to form a Nifilm 110. If the Ni thin film 108 and the Ni film 110 are then removedfrom the photoresist master 100, then as shown in FIG. 2(B), a stamper120 comprising an accurately transferred uneven pattern 106 can beobtained. At this point, the aforementioned Pd (106A) remains bonded tothe Ni thin film 108.

In this stamper 120, the pattern surface 206 is formed in the areacorresponding with the uneven pattern 106, and the mirror surface 207 isformed in the area corresponding with the non-uneven area 107.

Although not specifically shown in the drawings, the stamper 120 canthen be installed in a mold, and injection molding or the like is usedto manufacture an optical disc substrate having a final uneven patternwhich is created by transferring the uneven pattern as a negativepattern. In addition to using the stamper 120 to manufacture opticaldisc substrates, the stamper 120 can also be used as a master stamperfor preparing a mother stamper by an electroforming process, and thismother stamper can then be used to manufacture optical discs.

In addition, this mother stamper could also be used as a master forpreparing a child stamper, and this child stamper can then be used tomanufacture the optical discs. In other words, the stamper 120 of thepresent invention need not necessarily be used directly for themanufacture of optical discs, but may also be used indirectly for suchoptical disc manufacture, as the master stamper used in the preparationof a mother stamper or the like.

In the photoresist layer 104 of this embodiment, the provision of thelight absorption layer 103 enables a well defined latent image to beprojected, thus enabling a sharp uneven pattern 106 to be produced. Inaddition, because Pd is applied to the uneven pattern 106 and thesurface is then washed as preliminary treatments preceding theelectroless plating, a precise Ni thin film 108 that conforms to theshape of the uneven pattern 106 can be formed. In other words, theadvantages provided by the light absorption layer 103 are utilized totheir maximum effect.

The synergistic effect between the light absorption layer 103 and theapplied Pd enables the sharp uneven pattern 106 to be transferred to thestamper 120 with good retention of this sharpness, and as a result,sagging of the uneven pattern formed on the stamper 120 is suppressed.Moreover, the surface of the uneven pattern transferred to the stamper120 is smoother than that obtained in conventional processes, and thenumber of fine irregularities (fine defects) is markedly reduced. Byusing this stamper 120, optical recording media with suppressed noiselevels and good levels of recording and reading (playback) accuracy canbe produced.

Furthermore, even in those cases where exposure is stopped prior toexposure of the light absorption layer, a synergistic effect is stillobtained due to the applied Pd and the light absorption layer, andconsequently the sharp uneven pattern is able to be transferred to thestamper with good retention of this sharpness, in a similar manner tothat described above.

In addition, in the present embodiment only the case involving a Niplating treatment was described, but the present invention is notrestricted to this case, and other metal plating can also be used.

Furthermore, the stamper described above is applicable not only tooptical discs, but can also be applied generally to the manufacture ofinformation media, including magnetic discs (discrete media).

EXAMPLES Example: Stamper No. 1

Following formation of a layer of a coupling agent on top of a polishedglass substrate, a light absorption layer was formed by spin coating.The application liquid used was SWK-T5D60 (manufactured by Tokyo OhkaKogyo Co., Ltd.) containing 4,4′-bis(diethylamino)benzophenone as alight absorption agent. The applied layer was baked at 200° C. for 15minutes to cure the layer and remove residual solvent, thus forming alight absorption layer of 140 nm in thickness. Subsequently, aphotoresist (DVR100, manufactured by Zeon Corporation) was spin coatedonto the light absorption layer, and residual solvent was vaporized bybaking, thus forming a photoresist layer of 25 nm in thickness.

Subsequently, using a cutting machine manufactured by Sony Corporation,and targeting the formation of a groove pattern with a track pitch of320 nm and a groove width of 150 nm, the photoresist layer was exposedwith a Kr laser (wavelength=351 nm) and subsequently developed to forman uneven pattern, thus producing a photoresist master.

Following activation of the surface of the photoresist layer of thisphotoresist master using a surfactant, a catalyst (a Pd, Sn colloid) wasapplied as a preliminary treatment to electroless plating. Anaccelerator (HBF₄ solution) was then used to remove the Sn and achievedeposition of the Pd onto the photoresist surface, and the unevenpattern surface was then washed with ultra pure water (flow rate: 12l/min) thus completing the preparation for electroless plating.

The photoresist master was then immersed in a NiCl₂ solution, and a Nithin film was formed by electroless plating. Electroplating was thenconducted with this Ni thin film as a backing, thus forming a Ni film.The laminate formed from this Ni thin film and the Ni film was separatedfrom the master, the rear surface was polished, and the surface waswashed, thus completing production of a stamper No. 1.

Comparative Example: Stamper No. 2

With the exception of not performing the water washing step, a stamperNo. 2 was prepared in the same manner as the preparation of the stamperNo. 1.

Comparative Example: Stamper No. 3

With the exception of not providing a light absorption layer, a stamperNo. 3 was prepared in the same manner as the preparation of the stamperNo. 1.

(Evaluation Results 1)

The shape of the uneven pattern formed on each stamper was confirmed byinspection using an AFM (atomic force microscope). A silicon nitride(SiN) probe tip was used for the AFM probe. Measurement was conductedusing a non-contact mode, and the variations in atomic force between thesample and the probe were converted to an image.

FIG. 3(A) shows the AFM image of the stamper No. 1, and FIG. 3(B) is aline diagram showing the cross-sectional shape of the same image.Similarly, FIG. 4(A) shows the AFM image of the stamper No. 3, and FIG.4(B) is a line diagram showing the cross-sectional shape of the sameimage. In the AFM images, the dark areas of high dot density representthe concave sections within the uneven patterns, and the areas of lowdot density or the white areas represent the convex sections, and theseconcave and convex sections correspond with the convex and concavesections respectively of the uneven pattern on the photoresist master.In FIG. 3(B) and FIG. 4(B), the uneven patterns are formed with a pitchof 0.32 μm.

As is evident from comparing FIG. 3 and FIG. 4, in the stamper No. 1that was manufactured in accordance with the present invention, theeffect of the light absorption layer resulted in the formation of asharp pattern, and the effects of the Pd application and the waterwashing treatment enabled the pattern to be transferred faithfully tothe stamper.

(Evaluation Results 2)

The uneven states of the stamper No. 1 and the stamper No. 2, asmeasured by a scanning electron microscope (10,000×magnification), areshown in FIG. 5 and FIG. 6, respectively. By comparing FIG. 5 and FIG. 6it is evident that whereas no fine irregularities can be seen for thestamper No. 1, in the stamper No. 2, fine irregularities that appear asindentations with a width of approximately 1 μm are clearly visible atapproximately 3 μm and 8.5 μm along the horizontal axis. In FIG. 5 andFIG. 6, the unevennesses that appear with a pitch of approximately 0.3μm represent the uneven pattern formed in the present invention.

INDUSTRIAL APPLICABILITY

In the present invention, the light absorption layer contacting thephotoresist layer enables the formation of a sharp uneven pattern on thephotoresist master, and the Pd provided on the surface of this unevenpattern and the subsequent washing process enable the production of astamper with a pattern surface that is faithful to this uneven pattern.

1. A method of manufacturing a stamper for manufacturing an informationmedium, comprising the steps of: manufacturing a photoresist master byforming at least a light absorption layer and a photoresist layer, inthat order, on top of a substrate, irradiating light onto saidphotoresist layer to form a latent image from an opposite surface tothat which contacts said light absorption layer, and then developingsaid latent image to form an uneven pattern; forming a thin metal filmon top of said uneven pattern of said photoresist master; forming astamper by forming a metal film on top of said thin metal film, andseparating said thin metal film and said metal film from saidphotoresist master; and providing a metal catalyst on a surface of saiduneven pattern after manufacturing the photoresist master, activatingsaid metal catalyst, and then washing the surface of said uneven patternon which said metal catalyst is provided with a liquid, as preliminarytreatments to the step of forming said thin metal film on saidphotoresist layer.
 2. The method of manufacturing a stamper formanufacturing an information medium according to claim 1, wherein purewater is used as said liquid for said washing.
 3. A stamper formanufacturing an information medium, in a surface of the stamper anuneven pattern being formed in advance, the stamper being manufacturedby the steps of: manufacturing a photoresist master by forming at leasta light absorption layer and a photoresist layer, in that order, on topof a substrate, irradiating light onto said photoresist layer to form alatent image from an opposite surface to that which contacts said lightabsorption layer, and then developing said latent image to form anuneven pattern; forming a thin metal film on top of said uneven patternof said photoresist master; forming the stamper by forming a metal filmon top of said thin metal film, and separating said thin metal film andsaid metal film from said photoresist master; and providing a metalcatalyst on a surface of said uneven pattern after manufacturing thephotoresist master, activating said metal catalyst, and then washing thesurface of said uneven pattern on which said metal catalyst is providedwith a liquid, as preliminary treatments to the step of forming saidthin metal film on said photoresist layer.
 4. The stamper according toclaim 3, wherein pure water is used as said liquid for said washing. 5.A photoresist master comprising a substrate, a light absorption layerlaminated on top of said substrate, and a photoresist layer which islaminated on top of said light absorption layer and having an unevenpattern formed therein by forming and subsequently developing of alatent image, wherein an activated metal catalyst is provided on asurface of said uneven pattern formed in said photoresist layer, and thesurface of said uneven pattern on which said metal catalyst has beenprovided is washed with a liquid.